1. Field of Invention
This invention relates generally to detonators used in the downhole environment. More particularly, this invention relates to high temperature, non-primary explosive percussion detonators.
2. Description of the Art
A detonator is used in the downhole environment to initiate an explosive reaction for purposes of detonating an explosive device, such as a booster, a detonator cord, or a shaped charge. A detonator is used, for example, to initiate a detonation wave on a detonating cord to fire the shaped charges of a perforating gun.
Some detonators are ignited by an electrical mechanism. Once the detonator is at the appropriate depth in the wellbore, a signal is sent to the electrical mechanism, and the electrical mechanism transmits an electrical charge to the detonator thereby igniting it. Electrically actuated detonators, however, may malfunction when deployed in high temperature wellbores since the electrical components are susceptible to the high temperatures. It would therefore be beneficial to the prior art to provide a detonator that does not include components that are susceptible to the high temperature environments found in wellbores. In addition, electrically actuated detonators may also pose a safety hazard in the presence of specific frequencies of radio waves, since such waves may activate the electrical components and inadvertently ignite the detonator. The prior art would therefore also benefit from a detonator that cannot be inadvertently ignited by radio waves. Primary explosives are very sensitive to electrostatic radio frequency (RF) energy.
Some detonators also utilize very sensitive primary explosives, such as lead azide or silver azide. These primary explosives must be handled extremely carefully and have such great sensitivity that moderate or even slight motion or forces can ignite them. Primary explosives are a safety hazard. Therefore, it would be beneficial to the prior art to provide a detonator that does not include highly sensitive primary explosives.
Detonators used downhole must withstand extremely high temperatures and pressures for prolonged periods of time. Thus, all detonator components should be constructed to withstand such temperatures and pressures.
A conventional detonator may include a constricted constant radius cylindrical passageway between the ignition charge and the output charge. The purpose of this passageway is to enable the deflagration-to-detonation transition and to route this wave from the ignition charge to the output charge. However, detonation waves tend to propagate linearly and tend not to “turn corners” very well. Therefore, the inclusion of the cylindrical passageway in a detonator often times results in an energy decrease in the detonation wave as it attempts to enter and pass through the passageway. The prior art would therefore benefit from a detonator that includes a mechanism for routing the detonation wave from the ignition charge to the output charge without a corresponding loss in detonation wave energy.
Thus, there is a continuing need for an arrangement that addresses one or more of the problems that are stated above.